As you probably already know, the Windows Registry is a treasure trove of forensics artifacts that can come in quite handy during investigations and incident response. Many applications leave quite the trail, and I’ve decided to start documenting these less common sections in the registry and sharing the information that I find on my blog. We’ll start with Adobe Acrobat Reader:

In addition to recently accessed files showing up under the RecentDocs key, Acrobat Reader itself stores a list of the 5 most recently accessed PDF files in the user’s hive. This information can be found in the subkeys under Software\Adobe\AVGeneral\cRecentFiles. The subkeys found in this location are labeled cx (where x is replaced by the numbers 1 through 5), and under each of these subkeys you’ll find a value named tDIText which contains the full path and filename of the recently accessed pdf file. Every time a new PDF file is opened in Reader, any existing values found in cx are copied to cx+1 and any values that were in c5 are lost (of course, keep in mind that you may be able to use VSS to recover old hives). Unfortunately, Reader does not store date/time stamp values in these subkeys; however, you can get the date and time of the most recent file access (for the file information stored in c1) by reviewing the registry key’s last write time. For all of the other files described in the other subkeys, given no other supporting data, you’ll only be able to state that the pdf file was accessed but will be unable to definitively state when.

If/when I discover any other interesting artifacts left by Adobe Acrobat Reader in the registry, I’ll make sure to update this post with my findings. Feel free to leave me a comment as well if you have any additional Reader related artifacts that you review as part of your workflow…